1. Field of the Invention
The present invention relates to a pipeline processing type shaping apparatus and its method, and, more particularly, to a predetermined scheduling time calculation system for determining a predetermined scheduling time of a packet or cell for every connection according to a pipeline processing system in an interface from trunk communication equipment to access communication equipment that constitute a network.
2. Description of the Related Arts
Due to the recent increase of data traffic, the interface between trunk communication equipment and access communication equipment is becoming faster. In the interface of trunk communication equipment that is connected to access communication equipment, strict polishing and shaping for each connection needs to be executed based on a contract with the user. This connection corresponds to a VC (virtual connection) for an ATM (asynchronous transfer mode) interface, and corresponds to an IP (Internet protocol) for a POS (packet over SONET) interface. A token bucket system is cited as typical polishing processing or shaping processing.
Since this token bucket system requires the processing time of the algorithm, it is implemented by pipeline processing in conventional trunk communication equipment. The pipeline processing, as shown in FIG. 10, divides the algorithm of the token bucket system into a plurality of processing, and each processing is executed at a time for processing the minimum packet length T.
However, particularly in shaping processing, when the minimum packet that belongs to the same connection is continuously input, the following problem occurs. That is, for the shaping processing, in FIG. 11, when processing N terminates, a packet A of a connection in processing 1 is input and a predetermined transfer time of the packet A is determined. Accordingly, as shown in FIG. 11, the pipeline processing of a next packet B that belongs to the same connection is started after the processing N concerning the packet A terminates. Therefore, if the interval between the packet A and packet B is shorter than the time N×T until the processing 1 to N, the predetermined transfer time of each packet cannot be judged in real time. As a result, the shaping processing can be performed only for a connection of a comparatively low peak-rate such that the interval between the packet A and packet B exceeds N×T. As a result, it was difficult for a high-speed interface to shape the packet transfer for connection at a high peak-rate.